JP2011518665A - Fluid distribution and collection systems in multistage columns. - Google Patents

Abstract

A multistage column has a series of plates. Each plate supports a granular solid bed. Each plate is provided with a network for distributing the fluid. The network is constituted by substantially horizontal lines (6, 7, 10) having a plurality of branch stages of ranks 1 to N. An assembly of lines with ranks P to N is attached to the base surface of the plate. The line at the final stage N of the branch is in communication with a mixing chamber (8) located just below the base surface of the plate.
[Selection] Figure 7

Description

  The present invention relates to a novel apparatus for distributing and collecting fluids in a multi-stage column that utilizes a fluid flow in a solid particulate medium called a particulate medium.

  A multistage column is a column composed of a number of plates arranged along a substantially vertical axis. Each plate (referred to as a support plate) supports a granular solid bed. The fluid used in the column is sequentially passed through various successive beds. The fluid that passes through the continuous bed is called the main fluid and is distinguished from other fluids. Other fluids are generally added to the main fluid by a plate located between two successive beds and called a distribution plate.

  The granular solid of each bed is generally supplied via a distribution plate located upstream of the bed.

  The present invention relates to a distribution plate.

  In this specification, when the abbreviation “plate” is used, this means a distribution plate.

  The distribution plate is typically referred to as a distribution network for supplying or collecting fluid and one or more for mixing fluid injected or dispensed through the distribution network with the main fluid. Including a mixing chamber.

  The device of the present invention is composed of a plurality of distribution plates. The distribution network is at least partially in contact with the granular media.

  The present invention is essentially configured to position the distribution network of the distribution plate as close as possible to the support plate supporting the rank P granular bed to feed the rank P + 1 granular bed in the column. It is. What is meant by positioning as close as possible to the support plate is that the dead space below the lines constituting the distribution network of the distribution plate is minimized.

  The invention also relates to the possibility of adding a packing to the distribution network that separates the lines in contact with the distribution plate of the surrounding granular media.

  The present invention means that the interior of the solid bed of particles approaches plug flow, which can optimize the performance of various methods performed in this type of column, such as simulated moving bed (SMB) type adsorption. .

  The distributor is used in a multistage reactor or separation column and has multiple functions. This function includes, for example, injecting or dispensing fluid at any stage in the reactor or separation column.

  In general, this injection or extraction function is preferably performed in a manner that is balanced between the various regions of the column portion.

  The column part is generally divided into a certain number of parts. Each part must be washed in a manner that is homogeneous with respect to the other parts.

  This requires the use of a distributor having a specific profile, so that if each part has an equal surface area, the distributor will reach each part and supply (or remove) approximately equal flow on each part. To do. If the individual parts have different surface areas, the injected or dispensed flow is approximately proportional to the surface area of the related parts. If the associated column has large dimensions (eg, 5-15 meters in diameter), a network using larger or smaller branched lines is often used to draw fluid from the column exterior to the various plates of the multistage column. And then from one plate to the individual parts of the plate.

  The plate also has the function of mixing the main stream in the column and the stream injected by the network to supply a fluid having a homogeneous concentration to the downstream plate.

  Regarding the chromatography type or SMB type multistage column adsorption separation method, Patent Documents 1 to 4 exemplify configurations of distribution networks that supply plates of different heights in a column.

  The distribution network is fairly bulky and is used constantly and is located in the bed of particulate solid (catalyst or absorbent) to minimize the total column space.

  Alternatives that integrate the network into the distribution plate may be used, but such alternatives require the use of larger space plates. The total column space is even larger than when the distribution network is external to the plate and embedded in granular solids above or below the bed provided by the network.

  The choice of distribution network type, line dimensions and their location must meet various criteria.

Provide a distribution plate that is balanced across the distribution plate.

Leading in a synchronized manner in different zones of the plate, ie minimizing the dispersion of residence time in the network.

• Maximize the space of active solids with a network of as much reduced volume as possible.

• Use a network with sufficiently reduced fluid velocity to avoid the risk of vibrations that can damage the network and plate.

  To meet various criteria, large sized networks may be used, and placing the network in the granular media itself can disrupt the flow in the column. This is especially the case in processes using particulate solids where plug flow is desired.

  The term “plug” flow means a flow that is gradably homogeneous in velocity direction and magnitude, thereby minimizing axial dispersion in the device. It is particularly important that this objective be achieved in a simulated moving bed (SMB) separation process using one or more multistage columns.

International Publication No. 2006/027118 US Patent Application Publication No. 2006/0108274 European Patent No. 0074815 French patent invention No. 2792645

  The problem to be solved by the present invention is to improve the fluid flow in a column with multiple plates supporting a bed of granular solids, called a multistage column.

  As used herein, “improving the flow” means that the flow ideally approaches plug flow, that is, the axial dispersion of the fluid passing through the various continuous beds of the column is as small as possible. To do.

  The column typically constitutes a granular medium, and the fluid moving between the various plates is a downflowing liquid.

  The present invention comprises a collection of networks for distributing the fluid supplied to the column. Each distribution network is constituted by a substantially horizontal line 6 assigned to each plate of the column. The line has a plurality of branch stages of ranks 1 to N. An assembly of lines of rank P to N (P is selected in the range of 1 to N) is attached to the base surface of the plate. A line at the final stage N of the branch communicates with the mixing chamber 8 disposed immediately below the base surface.

  More precisely, if the distance of the lower end of one line of the network from the base surface of the distribution plate immediately downstream is H, H is in the range of 0 to 1/4 of the diameter of the line, The line can be said to be associated with the distribution plate.

  In the general case where the distributor network has multiple branch stages, these various stages start from the first line, designated 1, and move to the final branch stage line, designated N.

  Thus, the present invention resides in that at least part of the line from a certain branch rank P to the final branch rank N is attached to the distribution plate.

  Preferably, all the lines making up the rank 1 to N network are associated with the distribution plate.

  In this case, it can be said that the network is completely attached.

  In a preferred variant, the invention also consists in using a filling. The packing is disposed below at least a portion of a line that forms a network and separates the line from the surrounding granular media. Thereby, axial dispersion resulting from the presence of the lines in the granular medium can be minimized.

  The invention also resides in the simulated moving bed separation process using the apparatus of the invention, wherein the feedstock to be separated is any mixture of aromatic compounds containing 7 to 9 carbon atoms.

  The present invention also resides in a simulated moving bed separation process using the apparatus of the present invention wherein the feedstock to be separated is a mixture of normal paraffin and isoparaffin.

  Finally, the present invention resides in a simulated moving bed separation process using the apparatus of the present invention wherein the feedstock to be separated is a mixture of normal olefins and isoolefins.

  More generally, the fluid dispensing device of the present invention is used in any method. In the method, one or more multi-stage columns are used. Multi-stage columns require a fluid distribution system in each plate or part of a plurality of plates that make up the column, and are particularly used in simulated moving bed separation methods.

Preferably, the main fluid passing through the device has a density in the range of 600-950 kg / m ³ and a viscosity in the range of 0.1-0.6 cPo. The abbreviation cPo is centipoise (centipoise), that is, 10 ⁻³ kg / m. s. Represents.

For fluids related to application of the method of the present invention, the device of the present invention can provide an axial dispersion coefficient that is less than 3 × 10 ⁻³ cm ² / s at any point in the column bed.

In accordance with the prior art, the fluid flow is a diagram of a portion of a multi-stage column with a downflow. FIG. 3 is an explanatory diagram of a “rake” type distribution network that matches the prior art. It is explanatory drawing of a "蛸" type | mold distribution network which corresponds to a prior art. FIG. 3 is an explanatory diagram of a network having continuous multistage sub-divisions or branches according to the present invention. FIG. 3 is a detailed view of a distribution network in a granular solid bed, consistent with the prior art. It is sectional drawing which shows the part which corresponds to the part in alignment with a prior art, and follows the AA line of FIG. 5a, and shows the case where the distance between a network and its lower plate is not zero. FIG. 6 is a cross-sectional view showing a portion corresponding to the portion along the line AA in FIG. In accordance with the present invention, showing a portion corresponding to the portion along the line AA in FIG. 5a, the network is attached to the distribution plate and comprises a packing that eliminates dead space between the network line and said plate It is sectional drawing which shows the case. FIG. 5 is an explanatory diagram showing various embodiments of the present invention consistent with the present invention. FIG. 6b is an illustration showing an embodiment of the present invention that is consistent with the present invention and different from FIG. 6a. FIG. 6 is an explanatory view showing still another embodiment of the present invention that is consistent with the present invention and that is different from FIG. 6a. FIG. 4 is a diagram of a portion of a multi-stage column that uses a network consistent with the present invention and consistent with the present invention. It is explanatory drawing by computer simulation which corresponds to this invention and shows the phenomenon of the dead space reduction | decrease which can be reduced by this invention. 4 is a graph consistent with the present invention and illustrating the reduction in axial dispersion produced by the present invention. In this case, it is in the basic form (the line is in close contact with the plate) or in the preferred form (the line is in close contact with the supplemental packing), and the diameter of the line is 0.35 m in a fixed bed of 1 m width and 1 m height. It is a dimensional structure.

  The present invention is used in a method using a fluid passing through a granular medium divided into a plurality of beds. A container including a plurality of floors is generally cylindrical and thus constitutes a column. However, the columnar shape is not essential, and other shapes can be used. In this specification, the term “column” is used regardless of the outer shape of the column.

  Therefore, the present invention is applicable to a column having a plurality of beds arranged in succession. Such columns are referred to as multistage. The granular solid bed is separated by a distribution plate. This distribution plate injects or dispenses various fluids in the bed and carries the fluid from the outside of the column to the plate when injecting the fluid, and from the plate to the outside of the column when injecting the fluid. It is necessary to carry the fluid to the

  Lines for injecting or dispensing various fluids form a network at each distribution plate.

  Generally, the distribution plate is interposed between the granular solid beds immediately upstream and downstream thereof.

  The invention applies when at least part of the network of lines used is immediately upstream in the granular solid bed, as described above. That is, at least a portion of the distribution plate that provides the stage P bed is in the granular media of the stage P-1 bed.

  FIG. 1 is prior art and schematically shows a part of a column 1. Column 1 is further divided into a number of beds 2. Each bed 2 is constituted by a fixed bed of solid particles. The column is washed by the main downflow indicated by the downward black arrow.

  The floor 2 is separated by a distribution plate. The function of the distribution plate is to allow the dispensing or injection of main flow and miscible fluid flow from the upper floor.

  The distribution plate is generally further divided into panels 5 that collect fluid leaving the immediate upper floor. The plate is divided into panels to facilitate the mixing function of the fluid that is dispensed from the bed upstream of the plate and the fluid that is injected into the plate. Each panel 5 comprises an upper screen 4 or perforated plate that supports the upper floor and a fluid distributor 3 at the bottom of the panel to provide a particle bed downstream of the plate.

  This distributor 3 may be constituted by a screen or a perforated plate. Each panel 5 is connected to a supply network having one or more injection points. The injection network 6 provides an injection chamber 8. The infusion chamber is arranged in the panel itself and is provided with an opening in which fluid injection and dispensing is carried out in the panel itself.

  As can be seen from FIG. 1, according to the prior art, the injection chamber 8 is generally disposed inside the panel 5. In some cases, a portion of the injection chamber may enter the granular media of the floor by placing the injection chamber 8 on the upper screen 4.

  The shape of the panel is generally designed to provide good mixing between the main fluid from the upper floor and the fluid injected by the network before being distributed to the lower bed. The quality of fluid mixing and dispersion depends in part on the method of dividing the panel and the number of panels.

  There are many variations on how to divide a plate into panels.

  The distribution plate is connected to a distribution / collection network. This network is composed of various lines including at least one main line 6 and sub-line 7.

  To accommodate higher branches, for example, 3 or 4 other lines are possible, but for the sake of brevity, this document is limited to networks that include a main line 6 and a sub-line 7.

  According to the prior art, the main line 6 is generally located at a non-zero distance H with respect to the support screen 4, while the secondary line 7 has at least one downward substantially vertical portion. The horizontal line 6 is connected to the panel 5 of the distribution plate.

  FIG. 2 is an example of a “rake” type network line as viewed from above.

  Panel 5 divides the plate into parallel portions of approximately the same width.

  All the sub lines 7 are arranged in substantially the same direction corresponding to the length (or the larger dimension) of the panel 5.

  The main line 6 is connected to the sub-line 7 at different points distributed along the main line 6 and defining each sector. The end of the secondary line 7 provides an injection chamber 8. This injection chamber covers most of the length of the panel 5.

  FIG. 3 is another example of the prior art, which is a top view of a network of lines called “蛸” type.

  Here, the panel 5 corresponds to a fan-shaped portion.

  As shown in FIG. 3, the main line 6 thus directs the fluid from the outside to the center of the column and then distributes the fluid to the various sub-lines 7. As can be seen in FIG. 3, these sub-lines 7 extend radially through the circular distribution chamber by means of various sectors.

  FIG. 4 is another example of a line network using several consecutive subdivisions. The main line 6 is divided into two lines which themselves provide other sub-columns, thereby forming a three-stage network. Compared to FIG. 2, this network has three branch stages corresponding to line 9. Each line 9 provides two successive panels 5.

  Although these various network configurations are illustrated, the present invention is applicable to any type of network. Preferably, the present invention is applicable to a network having a plurality of branch stages as shown in FIG.

  FIG. 5a is a detailed view of the network and corresponds to a part of the horizontal subline 7h. The secondary line 7h is not in close contact with the plate, and continues to the other vertical portion 7v connected to the plate through the elbow portion. The non-zero distance that the horizontal portion 7h of the secondary line is away from the distribution plate 4 is represented by H.

  FIG. 5b is a cross section taken along the line AA in FIG. 5A.

  FIG. 5c is a cross section taken along the line AA in FIG. 5A. In this case, the lines of the subnetwork are in close contact with the associated plates. According to the invention, the distance H is equal to 1/4 of the diameter of the line 7h.

  FIG. 5d is a cross section along AA according to the invention, in which the sub-line of the network is in intimate contact with the distribution plate 4, and according to a preferred variant of the invention, the sub-line is separated from the granular bed by the packing. Has been. This means that the fluid does not move below the secondary line. That is, the sub-line closes a space located below the network line.

  FIG. 6 illustrates several embodiments of the present invention. The universal objective of the present invention is to minimize the space contained between the network and its associated plates.

  In FIG. 6a, two fillings are used that can block the space on both sides of the line 7h.

  In FIG. 6b, one U-shaped filling placed on line 7h is used.

  In FIG. 6c, a network of lines with a shape having a flat bottom surface is used.

  FIG. 7 schematically shows a part of the column 1. This part is subdivided into a plurality of granular beds 2. Each granular bed includes a fixed bed of solid particles.

  In the preferred variant of FIG. 7, the invention is applied when the main line 6 and the sub-line 7 are in close contact with the plate, i.e. the distance H is zero.

  More generally, if the network includes several branching stages from 1 to N, the present invention is such that part of the branching part is in intimate contact with the plate supporting the associated floor, and preferably all To ensure that the bifurcated portion of the plate is in intimate contact with the associated plate.

  In some cases, if it is very difficult to achieve the above conditions, the contact state is limited to, for example, only the P to N branch stage, and the 1 to P-1 branch stage is above the plate. At a non-zero distance H. According to the network of the present invention, it is only necessary that the final stage of the branch portion is in close contact with the plate.

  The importance of the present invention has been demonstrated with a series of hydrodynamic calculations performed on the two-dimensional structure shown in FIG. 8a. FIG. 8a shows various heights of the line relative to the bottom surface of the distribution plate. The various grayed zones correspond to the level of fluid recirculation through the granular bed. In particular, the black zone below the zone corresponds to a dead zone, i.e. a zone with maximum recirculation.

  However, a flow as close to plug flow as possible, that is, a flow without recirculation is required.

  The configuration being studied consisted of a granular bed having a height of 1 meter, a width of 1 meter, and a third dimension, a length much greater than the height and width.

  The particles constituting the granular bed were spherical non-porous particles having a diameter of 0.6 mm and an interstitial porosity of 32%.

  A line of 0.25 m diameter and 3 m length was embedded in the bed of particles.

  The distance (H) from the lowest point (lower end) of the line to the bottom of the floor (or the lower plate) was 0 to 0.65 m.

  When the line is in close contact with the lower plate (H = 0), a filling 9 corresponding to FIG. 5d is present under the line.

  The flow of water at ambient temperature was simulated in passing downward through the granular bed. The liquid velocity profile was flat at the floor entrance.

  The flow was simulated according to a porous media flow model denoted as “Brinkman-Forchheimer” model. Details of this model can be found, for example, in F Benyahia, “On the modeling of flow in packed bed systems”, Part Sci Tech 22 (2004), 367-378.

The axial dispersion obtained as a result of the various test configurations was measured by the axial dispersion coefficient Daxcm ² / s.

  The change in Dax as a function of the distance the line is away from the lower plate, ie, the height (H), is shown in FIG.

It is very clear from FIG. 8b that the axial dispersion coefficient Dax decreases as the line approaches the plate and passes a value of about 3 × 10 ⁻³ to 2 × 10 ⁻³ cm ² / s. It is.

  Height H was measured relative to the lower end of the line.

  The two points shown in white in FIG. 8b correspond to the present invention. The other points shown in black in Fig. 8b correspond to the prior art.

By flattening the line at the lower plate, the axial dispersion coefficient Dax reached a minimum value of 2 × 10 ⁻³ cm ² / s.

Furthermore, by separating the line from the granular medium and further reducing the dead space below the line, the axial dispersion is further reduced by placing a packing on the side of the line, from 2 × 10 ⁻³ cm ² / s. It decreased to 1.2 × 10 ⁻³ cm ² / s.

  The distribution device according to the present invention is suitable for accomplishing the distribution and collection of the fluid in a multi-stage column that utilizes the flow of fluid in a solid particle medium referred to as a granular medium.

1 column 2 beds 6, 7, 10 lines 8 mixing chamber (injection chamber)
9 Filling

Claims (11)

  A distribution device for supplying fluid to a multi-stage column, the multi-stage column having a series of plates, each plate comprising a network for supporting a granular solid bed and for distributing the fluid. And the network is constituted by substantially horizontal lines (6, 7, 10) having a plurality of branch stages of ranks 1 to N, and the collection of lines of ranks P to N is It is attached to the base surface, in other words, if the distance that the lower end of one line of the network is away from the base surface of the plate immediately downstream is H, H is from 1/1 of the line diameter. 4, P is any value between 1 and N, and the line of the branch final stage N is in communication with the mixing chamber (8) disposed immediately below the base surface apparatus. The dispensing device according to claim 1,
A distribution device in which all of the lines (6, 7, 10) constituting the distribution network of ranks 1 to N are attached to the base surface of the plate. The dispensing device according to claim 1 or 2, wherein
The plate is divided into M parts of substantially the same length of meridian panel shape, each part having at least one terminal of rank N of the distribution network. The dispensing device according to claim 1 or 2, wherein
The plate is divided into M parts approximately equal to a sector, each part having at least one terminal of rank N of the distribution network. The dispensing device according to any one of claims 1 to 4,
A distribution device in which at least part of the lines (6, 7, 10) of the distribution networks of ranks P to N are provided with a filling (9) for closing the space below the lines. The dispensing device according to any one of claims 1 to 4,
A distribution device in which all the lines (6, 7, 10) of the distribution networks of ranks 1 to N are provided with a filling (9) for closing the space below the lines. It is a usage method of the distribution apparatus as described in any one of Claims 1-6, Comprising:
In the simulated moving bed separation method, the feedstock to be separated is any mixture of aromatic compounds containing 7 to 9 carbon atoms. It is a usage method of the distribution apparatus as described in any one of Claims 1-6, Comprising:
In the simulated moving bed separation method, the feedstock to be separated is a mixture of normal paraffin and isoparaffin.   7. A simulated moving bed separation method using a distributor according to any one of claims 1-6, wherein the feed to be separated is a mixture of normal olefins and isoolefins. A simulated moving bed separation method using the distribution device according to any one of claims 1 to 6,
The method wherein the main fluid passing through the distributor has a density in the range of 600-950 kg / m ³ and a viscosity in the range of 0.1-0.6 cPo. A simulated moving bed separation method used by the distribution device according to any one of claims 1 to 6,
A method wherein the axial dispersion coefficient at any point of the column floor is less than 3 × 10 ⁻³ cm ² / s.

Images